I am not sure off hand if parallel make is a good idea with kernel-2.4.xx (it's fine for 2.6.xx, but on your system, 2.6.xx is unlikely to be a success). If you want to try it, though, you have to do it yourself, because to build the kernel, you use make directly; portage doesn't set anything up for you. So, you can try

Code:

make -j2 .....

As I say, I have heard that parallel make for 2.4 kernels is unlikely to work, but no harm in trying. (And for the kernel, anything more than -j2 will slow you down, I think.)